So because people in southern america (or perhaps all) get offended by the term it cannot be used, there is a world outside the US

No, because a large and politically active group of people who promote hate speech, bigotry, discrimination and oppression use the term, Mobileread has decided to eschew it.

And yes, this would be something of an annoyance to those who prefer the term "Grand Wizard" to "Grand Sorcerer." However, at Mobileread, the goal of politeness and public welcome trumps personal aesthetics; it's less important that the labels be pleasing to the people they don't offend than that they actively offend as few people as possible.

The believe, I expect, is that those who dislike "Grand Sorcerer" are welcome to change it to something they enjoy, and that they are not overly-burdened by seeing the label on other people's profiles. The same is not true in the other direction; those who dislike "Grand Wizard" are often not drawing on personal preferences, but a cultural history involving hate-filled oppression that was often expressed through murder.

Insisting that, because that cultural history doesn't span the globe, the mods should ignore it, implies a feeling of "bigotry and racism are just fine as long as they're not in my back yard."